Optical fibers are used ubiquitously in lighting and imaging applications, as well as in the telecommunication industry, where they provide higher data transmission rates over longer distances as compared to electric wiring. In addition, optical fibers are more flexible, lighter, and can be drawn into thinner diameters than metal wiring, allowing for higher-capacity bundling of fibers into cables. Surface coatings, applied via an ultra-violet (UV) curing process, are employed to protect optical fibers from physical damage and moisture intrusion, and to maintain their long-term durability in performance.
Carter et al. (U.S. Pat. No. 6,626,561) addresses UV curing uniformity issues for optical fibers having surfaces that are located outside a focal point of a UV curing device employing an elliptical reflector to direct UV light from a single UV light source positioned at a second focal point of the elliptical reflector, to the surface of the optical fiber. Curing uniformity issues can arise due to imprecise alignment of the optical fiber relative to the light source, or an irregular-shaped optical fiber. To address these issues, Carter uses a UV lamp structure employing an elliptical reflector to irradiate optical fiber surfaces positioned in the vicinity of a second elliptical reflector focal point with UV light from a single light source positioned in the vicinity of a first elliptical reflector focal point, wherein both the optical fiber and bulb are displaced slightly from the focal points. In this manner, the UV light rays reaching the surface of the optical fiber are dispersed, and the irradiation and curing of the optical coating can potentially be more uniform.
The inventor herein has recognized a potential issue with the above approach. Namely, by displacing the UV light source and the optical fiber away from the focal points of the elliptical reflector, the intensity of UV light irradiating the optical fiber surfaces is dispersed and reduced, thereby lowering the curing and production rates, and imparting higher manufacturing costs.
One approach that addresses the aforementioned issues includes a curing device, comprising a first elliptic cylindrical reflector and a second elliptic cylindrical reflector, the first elliptic cylindrical reflector and the second elliptic cylindrical reflector arranged to have a co-located focus, and a light source located at a second focus of the first elliptic cylindrical reflector, wherein light emitted from the light source is reflected to the co-located focus from the first elliptic cylindrical reflector and retro-reflected to the co-located focus from the second elliptic cylindrical reflector. In another embodiment, a method of curing a workpiece comprises drawing the workpiece along a co-located focus of a first elliptic cylindrical reflector and a second elliptic cylindrical reflector, irradiating UV light from a light source positioned at a second focus of the first elliptic cylindrical reflector, reflecting the irradiated UV light from the first elliptic cylindrical reflector on to a surface of the workpiece, and retro-reflecting the irradiated UV light from the second elliptic cylindrical reflector on to the surface of the workpiece. In a further embodiment, a method comprises positioning a workpiece along a first interior axis of a reflector, wherein the reflector comprises first curved surfaces having a first curvature and second curved surfaces having a second curvature, positioning a light source along a second interior axis of the reflector, and emitting light from the light source, wherein the emitted light is reflected from the first curved surfaces and from the second curved surfaces onto the workpiece.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.